1. Filed of the Invention
The present invention relates to a chloroisocyanuric acid composition having excellent stability during storage, comprising as the main components trichloroisocyanuric acid and/or dichloroisocyanuric acid, which is hydrolyzed in water to release active chlorine used for sterilization and bleaching and washing.
2. Description of the Prior Art
Chloroisocyanuric acids have been used from old as over wide fields as sterilizers, disinfectants or algicides for pool water, sewage, industrial water, cooling water, etc. or bleaching detergents for fibers, etc. As the chloroisocyanuric acid, there are known trichloroisocyanuric acid, dichloroisocyanuric acid, sodium dichloroisocyanurate, sodium dichloroisocyanurate dihydrate and potassium dichloroisocyanurate, etc.
The chloroisocyanuric acids have been provided in many preparatory forms such as powders, granules, spheres, tablets, etc. Further for the purpose of controlling dissolution in water, investigations have been made not only on shape but on preparations designed in their formulations.
However, chloroisocyanuric acids tend to generate chlorine gas or nitrogen chloride gas during storage or upon use, especially in a wet state and tend to cause reduction in effective ingredients, deterioration of packaging materials, etc. In addition, where alkaline compounds are formulated together with chloroisocyanuric acids, the acids are stable in a dry state but extremely vigorously decomposed in a wet state to accelerate generation of chlorine gas or nitrogen chloride gas. Furthermore, chloroisocyanuric acids are strong oxidizing agents so that when they are formulated together with other chemicals, the chloroisocyanuric acids per se often decompose to generate chlorine gas or nitrogen chloride gas. Among the chloroisocyanuric acids described above, the phenomenon is particularly remarkable with trichloroisocyanuric acid and dichloroisocyanuric acid.
As described above, mixing of the chloroisocyanuric acids with moisture or various compounds accelerates self decomposition so that it is not easy to determine the formulation compatible with the chloroisocyanuric acids. Accordingly, studies have been considerably made on properties of the chloroisocyanuric acids. For example, in order to prevent generation of gas by decomposition of the chloroisocyanuric acids, there have been proposed some reports or proposals that it is effective to reduce the moisture content in the product or to completely shield the moisture coming from the outside during storage, etc. However, any of them is unsatisfactory. For example, to manufacture the absolute anhydrous products is difficult in such a degree that it is impossible to industrially manufacture them. Even though metals are used as packaging materials that can be completely shielded from the air, decomposed gas sealed in would gradually accumulate during storage over long periods of time to cause corrosion of a wall, deformation or breakage, etc. of a container due to an increased pressure.
It has also been proposed to cover the surface of chloroisocyanuric acids with a film of inert substances, for example, paraffin wax or polyvinyl alcohol. However, the effect is not sufficient, as in the methods described above. Further when this is used for sterilization of pool water, oils are undesirably supplied in pool water. Furthermore, as is described in U.S. Pat. No. 3,061,549, there is a method in which the chloroisocyanuric acids are stored in a container made of paper board having coated thereon an alkali metal silicate. However, the container made of paper board coated with the alkali metal silicate is deteriorated in a short period of time but does not withstand storage over long periods and cannot sufficiently prevent decomposition of the chloroisocyanuric acid. It is also difficult to store the chloroisocyanuric acids over long periods in such a state that the acids are not changed.
Recently, some new proposals have been made. For example, in U.S. Pat. No. 4,334,610, there is proposed a method for stably storing the chloroisocyanuric acids in which compounds such as calcium oxide, sodium phosphate, ferrous oxide, magnesium oxide, zeolite, melamine, anmeline, etc. are charged in a porous bag having gas permeability and the chloroisocyanuric acids are packed in a storage container. However, this method encounters defects that the porous bag obstructs the opening of the storage container or the porous bag is sometimes broken, etc. when the chloroisocyanuric acids are taken out of the container.
Further in U.S. Pat. No. 4,389,325, there is proposed a method in which specific synthetic zeolite (main ingredient: aluminosilicate) is used to prevent the generation of chlorine gas. However, no remarkable effect is necessarily obtained.
With respect to the storage stability, the present inventors already filed an application directed to stabilizers comprising allophane compounds and activated charcoal, which matured into U.S. Pat. No. 4,715,983. The stabilizers are surely good but because activated charcoal is present, the product is colored black when mixed with the chloroisocyanuric acids. The coloration reduces commercial value of goods and the stabilizers should be put in a porous bag and provided for use. When the same problem as in U.S. Pat. No. 4,334,610 supra encounters.
In addition, trichloroisocyanuric acid and dichloroisocyanuric acid are extremely difficultly soluble in water, as compared to alkali metal salts of dichloroisocyanuric acid which is another chloroisocyanuric acid. However, trichloroisocyanuric acid and dichloroisocyanuric acid have the active chlorine contents as high as 90% or more and 70% or more, respectively, as compared to other chloroisocyanuric acids. Utilizing low solubility in water, trichloroisocyanuric acid and dichloroisocyanuric acid have been used in large quantities as sterilizers, disinfectants and slime controlling agents for pool water, sewage from septic tanks, industrial water or cooling water. Depending upon the quantity of water used or degree of pollution of water, or in the case of removing algae in water, removing ammoniacal nitrogen and further in the case of starting use of pool, etc., rapid dissolution and enhancement of active chlorine concentration is necessary; however, trichloroisocyanuric acid and dichloroisocyanuric acid themselves have the problem that their dissolution rate in water is extremely slow.
In order to improve the solubility of trichloroisocyanuric acid, various proposals have been made to solve the problem. For example, Japanese Patent Laid-open Publication No. Sho 54-160730 (160730/1979) utilizes that tablets prepared from trichloroisocyanuric acid and sodium cyanurate as well as a disintegration auxiliary are immediately disintegrated in water. Japanese Patent Laid-open Publication No. Sho58-46003 (46003/1983) proposes a chloroisocyanurate composition comprising trichloroisocyanuric acid, an alkali metal salt of dichloroisocyanuric acid and anhydrous sodium sulfate or sodium chloride which possesses rapid and long acting properties. Furthermore, the present inventors have proposed a composition of trichloroisocyanuric acid, cyanuric acid and an alkali metal phosphate (Japanese Patent Laid-open Publication No. Sho 58-59904 (59904/1983)) or a composition obtained by formulating isocyanuric acid and magnesium oxide or magnesium isocyanurate in trichloroisocyanuric acid (Japanese Patent Publication No. Sho 61-41883 (41883/1986)). However, trichloroisocyanuric acid and dichloroisocyanuric acid are more reactive than other chloroisocyanuric acids and sensitive particularly to moisture and alkaline substances. Therefore, when they are exposed to high humidity or mixed with alkaline substances, chlorine gas and nitrogen chloride gas tend to generate, resulting in reduction of effective ingredients and deterioration of packaging materials, etc. Thus, the above proposals also encounter the problem that attention should be paid to control during storage and upon use.